To determine the safety and the effects, if any, on sperm production of a new drug called EM574. EM574 is made by Takeda Chemical Industries Inc., Japan, and is being developed in the U.S. by TAP Holdings, Inc. Although EM574 is derived from the antibiotic Erytghromycin, it has no antibiotic activity. EM574 appears to accelerate the movement of the contents in the stomach and intestines. EM574 may be useful in the treatment of non-ulcer stomach problems, including heartburn, the treatment of slow stomach and intestinal movements because of diabetes.